The invention relates to a method of suppressing spurious signals in radar equipment and a device for carrying out the method.
The surveillance region of radar installations is generally divided, in azimuth and range, into a plurality of radar cells. For each radar cell there is an echo signal which is obtained by scanning the echo received by the aerial. To produce a decision as to whether the echo is a target or a disturbance, methods are used in radar signal processing whereby the average disturbance power is estimated locally and adaptively and whereby a constant and very low false alarm rate (constant-false-alarm-rate, CFAR) can be set as a result. A method frequently used calculates the arithmetic mean value from the amplitude values in the particular environment of the cell under test and derives a decision threshold therefrom. If the amplitude value in the cell under test exceeds this threshold value, the echo is recognised as a target, otherwise it is a disturbance. Behind this method is the implicit assumption that a statistically uniform disturbance process exists in the particular environment.
If echoes from two targets situated close together are present in the radar field, it can happen, when using this method of estimating, that the arithmetic mean value rises greatly in the environment under consideration as a result of the target echoes and both target reports are cut out as a result of the threshold value derived from the environment.